Ferry writes in the documentation that
it has taken him only three months to implement this and before this he
hadn't had any experience with Eclipse and Java. He writes that he found
some good starting points on OpenNTF.

Source Sniffer is a Domino Designer
extension written in Eclipse. It can search in the source code of a entire
application, it supports Java, Javascript, Lotusscript and Formula languages.
XPages are completely decoded so code can be found there too.